The present invention relates to a process for preparing a magnetic powder used for a magnetic recording medium.
Magnetic powders for magnetic recording media have been usually prepared by heating and reducing an iron oxide or an iron oxide hydrate which can be coated or doped with at least one of cobalt, nickel, tin, titanium, bismuth, zinc or antimony or its compounds, in a reducing atmosphere. In the process for preparing a magnetic powder, phenomena of melt bonding between particles and sintering are easily caused in the heating and reducing reactions whereby the improvements of magnetic characteristics such as coercive force, residual magnetic flux density, acicular ratio of the magnetic powder are limited.
In order to prevent the phenomena of the melt-bonding between the particles and the sintering, it is preferable to carry out the reduction at lower temperature. Thus, it takes a long time for the reduction so as to cause inferior industrial efficiency in the operation.